Coelho, a businessman, has said he plans to slash spending and foster growth

(CNN) -- Pedro Passos Coelho, a businessman and opposition leader, is set to succeed Jose Socrates as Portugal's prime minister after his party scored a convincing victory in Sunday's election.

According to official results posted online that accounted for more than 99% of all ballots, Coelho's Social Democratic Party had just under 39% of the vote. Socrates' Socialist Party was running a distant second at 28%, while the Popular Party had nearly 12% of the overall vote.

In his victory speech, Coelho announced the Social Democrats, which won 105 parliamentary seats, would form a coalition government with the Popular Party, which won 24 seats. He also promised to tackle Portugal's burgeoning financial crisis, including taking steps to meet European Union requirements for deficit reduction and revenue hikes in order to receive bailout funds.

"This is a night for Portugal to celebrate this change," he said. "We have our work cut out, but we aren't afraid of working."

In a speech Sunday night, Socrates -- who was first elected in 2002, and re-elected in 2009 -- acknowledged the loss and resigned as head of his party.

Portugal votes in snap election

"We have lived through extraordinary national and international circumstances but the facts are the facts: We lost," said Socrates, who wished Coelho and Portugal well going forward.

The early election was triggered by Socrates' resignation in March after the country's parliament rejected his austerity plan intended to ease the financial crisis. He remained on as the caretaker prime minister and hoped to muster more support in Sunday's election.

During the campaign, Socrates criticized "the obstruction" to his austerity plan as "intolerable."

But Coelho, in a March 30 guest column in the Wall Street Journal, headlined "Our Plan to Fix Portugal," criticized Socrates' plan for failing to spur growth while "imposing unacceptable sacrifices on the most vulnerable members of society."

"We voted against the ... austerity measures not because they went too far, but because they didn't go far enough," wrote the 46-year-old Coelho. "It was too much tax and not enough cost reduction."

We have our work cut out, but we aren't afraid of working.--Pedro Passos Coelho

He said his party plans to reduce Lisbon's public deficit to 4.6% of gross domestic product in 2011 (a figure that was 7% last year) and, by 2013, down further to 2% of GDP.

He added that he supported reforms aimed at making Portuguese businesses more competitive internationally. His plan, he said, would do so by reducing costs, increasing productivity and pushing viable industries by instituting "predictable tax policies, effective conflict resolution and reducing bureaucracy."

"We now have new hope for getting new growth in our economy, to show everyone that we are absolutely committed to reach the (EU mandates)," Coelho said Sunday night. "I hope this is a new step for Portugal to re-establish confidence."

Coelho, who was born in Coimbra and spent five years of his childhood in the then-Portuguese colony of Angola, will bring a business background when, as expected, he assumes the prime minister's job from Socrates in the coming weeks.

Active in Portuguese politics since 1980, most of those in Parliament and since 2010 as his party's leader, he has also made a name for himself in business. Since 2007, he has been executive director of Forment Invest, a firm focused on investing in environmentally friendly projects.

Like Greece and Ireland, the Portuguese government has already asked for outside help to address its budget crisis, one that's gotten worse in the worldwide economic downturn. That request to the European Commission was made in April.

The cost of Portugal's borrowings has gone up drastically since Socrates resigned in March.

Portugal was due to repay more than 4 billion euros ($5.68 billion) to investors in April, followed by payments of almost 5 billion in mid-June.